A convex lens is of ............ types

Options

A. 4
B. 3
C. 2
D. 6

Explanation

To solve the question regarding the types of convex lenses, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the types of convex lenses. We need to identify how many types there are.

2. **Identify the Types of Convex Lenses**:
- **Biconvex Lens**: This lens has both sides curved outward. It is the most common type of convex lens.
- **Pleno-convex Lens**: This lens has one flat side and one outwardly curved side.
- **Concave-Convex Lens**: This lens has one side that is concave (curved inward) and the other side that is convex (curved outward).

3. **Count the Types**: From the identification, we have:
- 1. Biconvex
- 2. Pleno-convex
- 3. Concave-convex

Thus, there are a total of **three types of convex lenses**.

4. **Select the Correct Option**: The options given were four, three, two, and six. Since we identified three types, the correct answer is **three**.

5. **Final Answer**: Fill in the blank with the number **three**.